Perforated exit regions for the reduction of micro-pressure waves from tunnels

Honglin Wang, Alan E. Vardy (Lead / Corresponding author), Dubravka Pokrajac

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)
225 Downloads (Pure)


The effectiveness of long, perforated exit regions in reducing pressure disturbances from railway tunnels is assessed. Such disturbances always occur, but their amplitudes are usually small. For the particular case of high speed trains, they can reach levels that would cause annoyance in the absence of suitable counter-measures. This risk is especially large in the case of long tunnels. The mechanisms causing the disturbances are described and the potential effectiveness of perforated exit regions as a counter-measure is demonstrated. It is shown that the effectiveness is sensitive to the number, size and distribution of pressure relief holes along the exit region, but that the most important parameter is the combined area of all of the holes. This parameter controls the balance between external disturbances alongside the perforated region and disturbances beyond the exit portal. It is also shown that the amplitudes of the external disturbances are strongly dependent upon the amplitude and duration of wavefronts arriving at the exit region as well as upon their steepness. This contrasts with the behaviour found for tunnels with simple exit portal regions.

Original languageEnglish
Pages (from-to)139-149
Number of pages11
JournalJournal of Wind Engineering and Industrial Aerodynamics
Early online date25 Sept 2015
Publication statusPublished - Nov 2015


  • Counter-measures
  • Micro-pressure wave
  • Perforated exit region
  • Pressure gradient
  • Rail tunnel
  • Sonic boom
  • Wavefront steepness

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Civil and Structural Engineering
  • Mechanical Engineering


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